The present invention relates to a glass wave guide element and a method of manufacturing the glass wave guide element.
In recent years, with development of optical communication technology, wavelength divisional multiplexing (WDM) communications have been employed. In order to separate wavelength multiplexed light transmitted inside an optical fiber, a communication of this kind requires an element which can select whether light having a certain wavelength is allowed to pass through or should be reflected by the element.
In regard to elements of this kind, there is an element which can select whether light having a certain wavelength is allowed to pass through or should be reflected by the element. In such an element, an ultraviolet light is irradiated onto a wave guide, having an optical fiber with germanium added thereto, to form a diffraction grating along the light transmission direction in the fiber by inducing refractive index change. Further, the Bragg wavelength is changed by changing the temperature of the diffraction grating by heating the wave guide using a heater.
However, a conventional wave guide element using an optical fiber is high in cost because the manufacturing process to mount a heater or the like thereon is complex. Further, the conventional wave guide element is essentially unsuitable for accommodating a reduction in size and an increase of integration. Further, the multiplicity of wavelength divisional multiplexing communications is being increased to 16 channels, and 32 channels in the future, and so the conventional wave guide element is unable to cope with the increasing multiplicity of channels from the viewpoint of cost and productivity.